Certain subterranean formations, such as shale gas reservoirs, coal gas reservoirs, and/or tight gas reservoirs, may include both gaseous hydrocarbons and adsorbed hydrocarbons. The adsorbed hydrocarbons initially may be adhered to and/or adsorbed on a structure, such as a rock matrix, that is present within the subterranean formation. However, upon production of a portion of the gaseous hydrocarbons from the subterranean formation, a portion of the adsorbed hydrocarbons may desorb from the structure, thereby transitioning to gaseous hydrocarbons and increasing an overall amount of gaseous hydrocarbons that may be produced from the subterranean formation. These adsorbed hydrocarbons that desorb from the structure also may be referred to herein as desorbed gaseous hydrocarbons and may form a significant proportion of the overall production of gaseous hydrocarbons from the subterranean formation.
It may be desirable to accurately and/or efficiently predict an overall amount of gaseous hydrocarbons that may be produced from a subterranean formation and/or a rate of gaseous hydrocarbon production under certain reservoir conditions. Thus, it may be desirable to accurately model the effect of adsorbed hydrocarbon desorption on production of the gaseous hydrocarbons.
Historically, models that predict production of gaseous hydrocarbons from traditional gaseous hydrocarbon reservoirs, such as gaseous hydrocarbon reservoirs that do not include a significant quantity of adsorbed hydrocarbons, have ignored the impact of adsorbed hydrocarbon desorption on the production of gaseous hydrocarbons. More recently, models that predict production of gaseous hydrocarbons from subterranean formations that include both gaseous hydrocarbons and adsorbed hydrocarbons have been developed. However, these models either rely on first principles calculations, which make them very computationally intensive, or significantly over-predict the production of gaseous hydrocarbons. Thus, there exists a need for improved systems and methods for modeling subterranean formations that include both gaseous hydrocarbons and adsorbed hydrocarbons.